Am I ok to assume that 48V x 210A = 10,080W (13.5Hp) will be the available power for my car ?

Hi Sy,

First off you have figured electrical power from the battery. And at 210A, the voltage will sag at least 3V, more depending on the battery type and size. Then you have to account for the losses in the controller, motor and drive train. Roughly that combined efficiency will be on the order of the hp to kW conversion, ~.75. So, 45V * 210A = 9.45kW giving you about 9.5 hp to the drive wheels.

Realize this is the rated power from your controller. Peak power will be higher.

I am not familiar yet with Lead Acid battery, can they provide 150-200A for 15 to 30 minutes without overheating ?

Pb-Acid batteries large enough to give you the stated range at 50% DOD should be able to do that current without heat issues, IMO.

Good luck,

major

 

thank you major

Time for some pics:

The car

Engine bay (12V battery during tests only)

Adapter plate and chain (top view)

Tranny adapter and chain (bottom view)

Controller (mounted were ICE rad was before)

Motor label

Don't worry about rust seen in pictures. The car sit for 2 months outside waiting to be sold. It's only on surface.

 

I will do away with the 2:1 ratio. Considering your low (and realistic) speed expectation, rather run the car in the highest gear if even possible with
that "small" motor.

Is there only one bearing on the adapter plate? If you are keeping the clutch
the flywheel will wobble very soon. Also the transmission input shaft is not designed to take the weight and overhung load of the flywheel , your motor or
ICE is supposed to take the load. Modify the adapter plate and mount the motor
directly on the transmission.

There might be other reasons why the previous owner abandoned the project.

 

Is there only one bearing on the adapter plate? If you are keeping the clutch
the flywheel will wobble very soon. Also the transmission input shaft is not designed to take the weight and overhung load of the flywheel , your motor or
ICE is supposed to take the load. Modify the adapter plate and mount the motor
directly on the transmission.

There is one outside and one inside also. It seem pretty robust to support the flywheel instead of the ICE.

Yes I could modify the adapter plate but for now I will try to limit the motor RPM to around 3k and that will mean 6k at the flywheel.

This is my first project to learn the base, the programming, the battery, the charger... I've got that car pretty cheap and I want to start somewhere without to much modifications.

In the future (I should say in my dreams), what I want, is a street legal "monster" like John Wayland's White Zombie... but I'm a long way from there regarding money and experience so I must begin somewhere. But in my previous car, in about 4 years, I went from a stock 93 Civic that cost me 1k$ and ran the 1/4 mile in about 18sec all the way up to a drag ready 19k$ custom Civic that run 12.9@105 in N/A form at the drag strip. (all done by myself including engine swap)

wow, that motor is HUGE considering the output! but at 48v, I guess that's what your gonna get. depending on how much rear seat and cargo area you wanna give up you could go with 4 big 12v sweeper batteries, or 6 good 8v golf cart batteries for a little more range. I have had great luck with us batteries (see http://www.usbattery.com/)

The chain drive would have me pretty nervous... I rode in a home-brewed EV with 3 small motors chained together, and it was LOUD with those chains flying around!

Depending on funding, you might wanna yank out this (failed?) drivetrain and go with a simple DC setup at 96 or 120v for better drivability?

Thank you for the batteries recommendation... as for the chain I don't know yet but I'm not worried too much because I will not go very fast and I will lower the motor RPM and use a different gear if needed.

For the drivetrain, I thing that I will keep that AC setup for now. Time and tests will tell if it's "drivable".


Thank you guys... any comments welcome !

 

wow, that motor is HUGE considering the output! but at 48v, I guess that's what your gonna get. depending on how much rear seat and cargo area you wanna give up you could go with 4 big 12v sweeper batteries, or 6 good 8v golf cart batteries for a little more range. I have had great luck with us batteries (see http://www.usbattery.com/)

The chain drive would have me pretty nervous... I rode in a home-brewed EV with 3 small motors chained together, and it was LOUD with those chains flying around!

Depending on funding, you might wanna yank out this (failed?) drivetrain and go with a simple DC setup at 96 or 120v for better drivability?

 

How far are the bearings apart?
Have you actually ran the flywheel at 6000 RPM?
You might still damage your transmission meaning more costs and more time lost.

 

I don't know I haven't removed anything yet. For the 6k see below.

You'll get 6k at the flywheel but at half the torque. And 6k rpm in 5th gear will be like 100mph+.

It'd be very inefficient to go from 3k rpm to 6k rpm back down to 2k rpm in 1st gear. But I understand that you don't want to mess around with it since it's already built. Since you only have 25hp or so max power, I don't think your transmission will break from the tension of the chain so you should be okay driving it around. It's just not the most efficient design.

Okay , that is what I thought about the torque. I'd prefer to run the motor at low RPM to gain max torque (see specs sheet below) but someone suggested that I run it higher ?! *.

What I was told by the previous owner is to run at 1500-1700 rpm to have max torque and the 1:2 ratio would provide ~3000 rpm at the flywheel so in 2nd or 3rd gear I would be able to drive at reasonnable speed.

Now I'm a bit confused

* see my other thread for other recommendations I've received: http://www.diyelectriccar.com/forums/showthread.php?t=38066

 

Yes I could modify the adapter plate but for now I will try to limit the motor RPM to around 3k and that will mean 6k at the flywheel.

You'll get 6k at the flywheel but at half the torque. And 6k rpm in 5th gear will be like 100mph+.

It'd be very inefficient to go from 3k rpm to 6k rpm back down to 2k rpm in 1st gear. But I understand that you don't want to mess around with it since it's already built. Since you only have 25hp or so max power, I don't think your transmission will break from the tension of the chain so you should be okay driving it around. It's just not the most efficient design.

 

I did not mean that the torque will damage the transmission , but rather the
vibrations and run out. Judging from the quality of the welds I will undo as much as possible.

 

ha ha... ok... I too was doubting of the welds, but aligment is supposed to be done with 0.001 tolerance.

"run out" I'm not sure what you mean ?! I speak french so my english is not perfect .

Then again I will try to run at low rpm in a higher gear to minimize vibrations. The car itself will not go at high speeds. If I see / sense too much vibrations, I will surely advice and consider going with a more direct drive.

 

You're right SyCo, low RPM on that motor will give you more torque. For example, you'll get 210NM torque at 1000 rpm, and only about ~90NM at 2000rpm. You would probably get more torque by just doing the 2:1 ratio to the flywheel which will have your motor running at 1000rpm, 210NM torque and give you 2000rpm at about 105NM torque - 2-5% losses.

So running the motor in low RPM is better, however I'd do it with the transmission by starting in 3rd and going to 5th instead of adding 5% additional losses with a 2:1 ratio and then using 1st to 4th gear.

1500rpm in 5th gear will probably get you about 50mph which would be perfect if you had the motor directly connected to the transmission since 15HP wouldn't get you going faster than that. Of coure, it's not worth changing now that the chain drive has been built unless it damages your transmission. And I rally can't guess if it would. I'd rather the welds break than the transmission though

 

@icec0o1, ... okay, that is what one of my friend told me also. I will try working with torque since everything is already in place aka 1:2 chain drive. If I'd do it by myself it would have been direct to the transmission like you've suggested.

At least I've received the motor learning procedure from Curtis and I will be able to confirm my settings .

Next thing will be the batteries selection. I've been looking at Costco's biggest batteries which are "900 cranking amps" and are quite big in size but I don't find the AH rating ?! Does it have to do with the Style/Size written on the batteries like 78DT-120 or something else ? (still newbie here )

 

I've been looking at Costco's biggest batteries which are "900 cranking amps" and are quite big in size but I don't find the AH rating ?!

Look for the words Deep Cycle. Batteries advertising cold cranking amps are most likely cranking batteries. Good for 30 or so deep cycles. Real deep cycle Pb-acid batteries are good for 300 or more deep cycles. Look for golf cart batteries or similar.

Check out the Battery section of this forum.

Regards,

major

 

I did my first test drive yesterday, with full acceleration I read ~275A DC on the Fluke meter. At half throttle, I read 150A DC.

So 48x275=13,200W (~17hp) and 48x150=7,200W (~9hp). I think that is within the specs of my motor.

In second gear acceleration was surprising, even in third gear but top speed was not that fast ~15-20 mph. I did not try 4th because I did not have enough juice. Keep in mind tests were done in a small street and I may have reached a better top speed with more road available or in 4th/5th gear since I'm running low RPM on my motor.

I will have to get some decent batteries to do more tests.

 

That's sweet. Congrats on the good buy. Do you know what RPM your motor was running at at 20mph and 3rd?

 

Unfortunately not ... It was at night and I did not have enough light to look a the programmer (monitor) and the meter.

I will, of course, do some tests during the day and keep notes of everything I can

 

Here is an estimate I'm trying to do of my Ah requirements using some wiki information.

Since I'm using a 48V high amps AC system, I've guessed 400Wh/mile efficiency (anyone one with more accurate value for my efficiency is welcome to chime in ).

I want to be able to travel 20 miles.

So total energy required at 100% throttle (275A) is 275x20=5500 or 5.5Kwh.

Since my voltage is 48V this means my Ah rating will be the total energy divided by the voltage. In this case 5500W / 48V = 114.5Ah

I plan on going 80% DOD. So 114.5Ah x 1.25 = 143Ah

Now add Peukert effect. 143Ah x 1.8 = 257Ah

This is the worst case scenario for my energy consumption. I hope, after more tests, to get lower amps draw. In the meantime, I think that to reach my required distance, I would need something like 8 Trojan T-1275 rated at 150Ah. Two series of 4 batteries (total 48V) wired in parallel (total 300Ah).

Bank1: 12V-12V-12V-12V (48V, 150Ah)
Bank2: 12V-12V-12V-12V (48V, 150Ah)

Bank1 + Bank2= (48V, 300Ah)

Is this a realistic estimate ?

Note: I have not included my top speed since I'm using 100% throttle and I'm assuming I will need most of that to reach at least 30 mph.

EDIT: Btw I've got some price for local batteries...
Trojan T-105 6V, 225Ah @ 154$
Trojan T-1275 12V, 150Ah @ 224$
DEKA 8AGC2 6V @ 241$
DEKA 8GGC2 6V, 185AH @ 273$
T-105 reconditionned (1 year warranty) @ 61$
8AGC2 reconditionned (1 year warranty) @ 70$
Are those good prices ? What about recon batteries ?

 

I think the chain will stretch pretty fast, you really need a slightly longer chain with a tensioner to preserve its life.

 

You're right, I did not talk about it but the chain is a bit loose. I was given a sprocket with a bearing. Yesterday I bought a tensioner and fitted the sprocket to it . The only thing left is to mount it on the car.

@icec0o1, thank you for correcting my math. I will also need more tests to accurately evaluates my needs. I also thought about the reconditioned ones for the price. In real life I need precisely 10 miles total to my work and back. Average speed is 25-30mph and there are some steep slopes. I was thinking that 20 miles was safer but it is maybe too much for my needs. I think that by adding efficient driving techniques with real required mileage, 8 x T-105 would make it for me.

 

You have the math a little wrong there.

watts = amps * voltage

You have to go backwards. Based on your efficiency estimates, you say you'd use about 400Wh per mile which is probably a good guess. You want to go 20 miles so 400 * 20 = 8,000 Wh or 8Kwh.

8,000Wh / 48volts = 166 amp hours * 1.25% = 207 amp hours for 80% DOD to 20 miles.

If you want to max out the amps and add the Peukert effect,
207 * 1.8 = 373 amp hours.

If you're willing to drive very efficiently and maybe 15 mile range, go for 8 T-105 batteries for 225AH.

For a 20 mile range, you can go for 8 T-1275, 4 in parallel for 300amp hours. Or 16 T-105's would give you 450Ah but that'd be pretty heavy.

I would be tempted to buy the reconditioned ones. They're less than half the price and I would think they'd last longer than half of brand new ones. They'd only last a year or two max anyways so warranty is good (300 cycles or so).

 

Quick update, I've cleaned my setup. Everything was loose for test purpose but now I'm starting to clean up everything.

Here are some pics which I think look a lot nicer

(Don't worry, my 12 volt battery will be fixed with something safer than an elastic luggage strap.)

Now I need some loom to make it even cleaner.

My next step should be my vacuum system for the brakes .

I'm still looking at a cost effective solution for a 48VDC to 12VDC converter. I saw some in Golf Cart parts on Ebay

 

Ok Spring Update !!!

So my EV was asleep all winter but now the project continues.

I've bought some new batteries. Costco/Kirkland Marine Deep Cycles (125Ah with 12 months replacement and pro-rate after) (4 of them).

With more powerfull batteries I'm now able to accelerate much more quickly since more Amps are available (400-425A at times on my meter). Accelerating and running on flat ground is a breeze.

I ran 6 miles to ~40% DOD. I was accelerating hard and climbing light slopes. Of course batteries are not cycled yet but I seem on a good way to reach my 10 miles commute each day.

Now I really need to do more tests in slopes (I live in a city full of slopes). Preliminary tests showed that I don't have much power to spare in steep grades. But half of my commute is going down and half is going up so it should almost be okay.

 

SyCo how's the performance of the car up to 40mph with the Lead acid batteries?
Any voltage sag when accelerating?
Great cost effective car!

 

Hi, my EV Accent is not running currently (I'm using my Zenn instead). For the short duration I've used it, I think I recall not much of a voltage sag but I'll only be able to confirm 100% if/when I put new batteries in the car.

Thanks !

 

Hi SyCo,

I just bought a Hyundai Excel 2002 exactly the same as you to do an electric conversion.
It is really fun to see the same car but already converted. Nice pictures!!!

I am from Québec (Saguenay): I think you are also form Québec...

I am actually searching how to pull out the engine and if it is possible without pulling it with the manual transmission. Do you now it?

I will follow your thread.

 

Hi welcome to the forum ! .. Unless I've missed something, they were no "Hyundai Excel" in 2002 so either your year is wrong or you simply made a typo with the model

First, my car is now sold but I still have some information about it. I also currently own a Zenn NEV that I use daily. ZENN ev

About pulling out the engine and keeping the tranny in the car, I'm note sure... In my case the engine was already out when I've bought it. From what I recall, that type of chassis have a front and rear support for the tranny itself. So you may need to remove everything at once, if it is easier, and then drop the tranny back in the car. Normally, such a small transmission it is not too heavy (less than 100lbs) so it might be the better route.

Oh and btw I'm also in Saguenay, and of course I speak french. If it's easier to you you can send me a PM or reach me by email at sycotuning @ hotmail . com